The present invention relates to integrated circuit (IC) package technology and more particularly to improved heat dissipating from integrated circuit packages.
As integrated circuits (ICs) become smaller and faster, the amount of heat generated per square inch may increase accordingly. Therefore, one of the challenges presented to IC package designers is to dissipate heat. An IC package typically includes an IC mounted on a package substrate. A heat dissipating device, such as an integrated heat spreader (IHS) or a thermal plate, may be coupled to a backside surface of the IC, in an effort to remove heat from the IC. Imperfections in the mating surfaces of the IC and the heat dissipating device may result in small gaps of air between the devices. Because air is a poor conductor of heat, these gaps may serve as a barrier to heat transfer. A thermal interface material (TIM) with a higher thermal conductivity than air may be disposed between the IC and the heat dissipating device in an effort to fill these gaps and enhance heat transfer.
The TIM is typically made of a polymer material in combination with filler components made of a thermally conductive material, such as metal or ceramic. The polymer material may promote adhesion with the IC and the heat dissipating device and may bind the filler components together. Because the polymer material typically has a low thermal conductivity, the thermally conductive filler components may provide the main path for heat transfer. Therefore, heat transfer may be dependent on physical contact between filler components and the surfaces of the IC and the heat dissipating device, as well as physical contact between adjacent filler components in the bulk TIM.
However, layers of polymer material may prevent direct physical contact between filler components and the surfaces of the IC and the heat dissipating device, which may increase contact thermal resistance at these interfaces. Further, layers of polymer material may also fill gaps between adjacent filler components which may prevent direct physical contact between the surfaces of the adjacent filler components and may increase bulk thermal resistance of the TIM.